Insects of Britain and Ireland: the genera of Syrphidae (hoverflies)
Eurimyia, Helophilus p.p.
Adult flies. The flies resembling a potter bee (A. contracta and A. transfuga, cf. Epeolus spp.), or megachilid bee-like (A. lineata, cf. Coelioxys inermis), or not suggestive of mimicry; black or brownish, marked with tawny, greyish or whitish, with a yellow head; small to medium sized; 8.8–10.6 mm long. Wings 5–8.25 mm long.
The head about the same width as the thorax. The face ground-coloured at least part yellow; not flat or retreating between antennae and mouth; with a central knob; produced below and extending beyond the antennae; drawn out into a horizontal cone as long as the rest of the head (A. lineata), or not elongated horizontally into a cone as long as the rest of the head; with tubercles; elongated and tuberculated. The eyes depicted as bare. Antennae relatively short, drooping; with their bases approximated (seated on a tubercle); black, or ferruginous. The third antennal segment ovoid or orbicular. The antennal bristle dorsal; much longer than the third segment; simple (bare or pubescent).
The humeri hairy, and readily visible behind the head. The thorax patterned; usually black with pale longitudinal and transverse markings which produce a skull-like figure; with longitudinal stripes (usually, with 4 slender pale or luteous dust stripes), or without longitudinal stripes (rarely, in some individuals). The scutellum somewhat convex, with undefined edge; brownish, ferrugineous or tawny. Wings plain; divergent in repose (slightly grey or colourless). Wing veins R2+3 and R4+5 not forming a closed cell. The anterior cross vein R-M in cell R5 crossing it at or beyond the middle of the adjoining discal cell (near the middle). Vein R4+5 with a conspicuous curve projecting into the cell R5. The lower outer marginal vein more or less parallel with the posterior wing margin. The upper and lower outer marginal cross veins more or less continuous. The upper outer marginal cross-vein gently curved (almost straight); not re-entrant. The hind femur distally with neither a triangular plate nor a tooth.
The abdomen wider than the thorax to narrower than the thorax (wider in the female); ovate, or more or less fusiform, or linear. The male abdomen with 4 visible segments. The abdomen contrastingly patterned. The tergite patterning involving 2 to 4. The colour-patterned tergites marked with tawny (mainly), or whitish, or silvery or greyish. The dorsum of tergite 2 with golf-club shaped spots, or without golf-club shaped spots; exhibiting a wineglass-shaped black area, or without a wineglass-shaped black area. The dorsum of tergite 3 with a pair of pale marks in the form of a moustache, or not marked in the form of a moustache. The tergite bands medianly interrupted; narrow; straight or curved. The spiracles of the third abdominal segment borne at or near the anterior corner of each side. The pale abdominal markings opaque.
Larvae and pupae. The larvae long tailed, tapering posteriorly into a long breathing tube; tailed. The anal segment abruptly constricted basally into the long, narrow tail; at least as long as the rest of the body (rat-tailed maggots, distinguished by a line of setae along the lateral margins of the body). The larvae scarcely flattened; brown, plain; without thoracic hooks; mouth without triangular sclerites; anal segments with lappets. The larvae aquatic; saprophagous; in decaying vegetation (especially in the remains of Typha in pools and ponds).
General comments. The hind tibiae with two black rings.
Classification. Subfamily Milesiinae; tribe Eristalini.
British representation. 5 species in Britain.
Illustrations. • A. lunulata and A. transfuga: Verrall. • A. lineata: Verrall.
To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. Insects of Britain and Ireland: the genera of Syrphidae (hoverflies). Version: 28th July 2015. delta-intkey.com’.